The type of vessel with subaqueous hulls is, in fact, constructed with a view to being affected at sea as little as possible by the wave motion, thus to achieve a quiet position by the motion-limiting properties with regard to pitching, rolling and heaving. This thanks to the fact that the buoyancy is substantially derived from hulls located entirely below the water level which, only by means of columns, are connected with the working platform borne above the water level. On the other hand, such a vessel has a comparatively low stability. For use as a drilling island this is no objection since the fixed drilling tower is positioned centrally, but on a similar ship only cranes with a low lifting power can be applied because an eccentric load causes a considerable list.
It would be of great advantage if the favorable properties of a vessel of the abovementioned type as to its quietness in a rough sea could be used for a so-called "work-vessel" provided with a derrick and/or cranes suitable for carrying out jobs at sea, for instance for erecting and dismantling production platforms and for other off-shore transport functions.